The major thrust of this grant still centers around structure, function and pathology of basement membrane. In the coming year, we will complete the studies of the biosynthesis of basement membrane using isotopically labeled amino acids, carbohydrates and bridging sugars to identify the organella pathway through normal and neoplastic epithelial cells. Concomitantly, an assay for the enzymes responsible for the degradation of basement membrane will be completed and the turn over of basement membrane will be studied first in the breast and then in the glomerular basement membrane. Parietal yolk sac carcinomas still serve as the model system for the study of basement membranes and we are in the process of identifying mutants capable of synthesizing fragments of the basement membrane molecule. These studies will also branch into studies of the cell of origin of cancer, and mode of development of tumors. Further experimentation with the enzyme labeled antibody technique for the ultrastructural localization of antigen will be undertaken, although major emphasis in the coming year will be placed upon adaption of enzyme labeled antibody as a substitute method in competitive inhibition immunoassays for trace amounts of molecules. Currently nanogram amounts of hormone can be measured in a dip stick type of procedure which may revolutionize our ability to search for basement membrane enzymes, or fragments of basement membrane molecules in various pathological conditions.